⚠️ TOP 7 RESTORATION MISTAKES

**❌ GOI polishing paste on silver** — ruins it permanently
**❌ Felt wheels, grinding, microfiber cloths** — leave scratches
**❌ Open chemical baths** — fumes can damage your whole collection nearby (real case: losses of 200,000 ₽)
**❌ Mixing different metals** in an ultrasonic bath or solution — causes electrolysis
**❌ Over-soaking in acid** — the metal itself starts to dissolve
**❌ Using a scaler on silver** — scratches the surface
**❌ Dry cleaning with fiberglass brushes** — always use soap and water!

✅ Pre-cleaning checklist

[ ] Have you identified the metal type?
[ ] Does it actually need cleaning?
[ ] Is the coin not a rare one?
[ ] Do you have protection (gloves, goggles)?
[ ] Is the rest of your collection safely covered/sealed off?

📋 Reagent reference table

SubstanceWhat it's forTimeRisk --------------------------------- Bar soapDirt and grimeDaysLow Baking sodaOxides5–15 minLow Citric acidSilver oxidesHours–daysLow AmmoniaSilver oxides2–3 hLow Phosphoric acidCopper oxides45 minMedium Azelit (rust remover)Black crust1 minLow ThioureaBlack silver patina (silver sulfide)15+ hHigh Pemoluxe (abrasive cleaner)OxidesOn the spotMedium

Remember: it's better to leave a coin dirty than to ruin it forever.